FRIDAY, Feb. 28, 2014 (HealthDay News) -- Medicines commonly used to control asthma may increase the risk of a potentially serious sleep problem in some people, a small, early study suggests.

"Inhaled corticosteroids may predispose to sleep apnea in some asthma patients," said study author Dr. Mihaela Teodorescu, an associate professor of medicine at the University of Wisconsin School of Medicine and Public Health, in Madison.

In sleep apnea, breathing periodically stops during sleep, for a few seconds or even minutes at a time, according to the U.S. National Heart, Lung, and Blood Institute. The pauses can occur as often as 30 times or more in a single hour. In the most common type of apnea, the airway becomes blocked or collapses during sleep. If untreated, apnea can increase the risk of high blood pressure, heart attack, stroke and other problems.

However, the new study linking asthma medicines with an increased apnea risk was very small -- including just 18 patients. And the researchers found a link, not cause and effect, and don't yet know what that connection means.

An expert not involved in the study was skeptical of the findings, emphasizing that more work is needed.

Teodorescu agreed, and is continuing to look at the medicines.

In the new study, the 18 men and women evaluated were taking 1,760 micrograms a day of inhaled fluticasone (Flonase). (Another inhaled corticosteroid is budesonide, or Pulmicort.)

The researchers monitored the men and women for changes in the "collapsibility" of their upper airways during sleep and their tongue function. Three patients had the amount of fat in their soft palates measured with MRIs, which found a redistribution of fat to the neck area, which can narrow the airway.

All the patients had changes in their tongue function and upper airway consistent with sleep apnea, said Teodorescu, who is also the director of the James B. Skatrud Pulmonary Sleep Research Laboratory at the Middleton Memorial Veterans Hospital, in Madison, Wisc.

Some patients were more affected than others, Teodorescu said. More vulnerable, she said, were the patients who were mid-30s or older, men and those whose asthma was poorly controlled at the start.

Teodorescu decided to study the effect of the corticosteroids after she said she found growing evidence that sleep apnea is more prevalent among people with more severe asthma. The current study is a pilot study.

The study appears in the February issue of the Journal of Clinical Sleep Medicine.

One expert called for more research into the link.

"We need a larger study," said Dr. Len Horovitz, a pulmonologist and internist at Lenox Hill Hospital in New York City. The steroids studied by the Wisconsin researchers are a mainstay of treatment for moderate asthma, he said, and can work well to control the asthma.

The findings cited by the researchers -- floppiness of the tongue and oral membranes -- would typically also be linked with noticeable speech changes and vocal quality changes, he said. The researchers should consider including evaluations by a speech pathologist and ear-nose-throat specialists, he added.

"Time will tell when we look at a larger study," Horovitz said.

Michele Meixell, a spokesperson for AstraZeneca, said that her company's Pulmicort (budesonide) is safe and effective "when used in accordance with the FDA-approved indications."

Meanwhile, Teodorescu said if asthma patients are getting control of their asthma on prescribed steroids, "they should continue." She suggested the medicine and dose be tailored to each patient's needs.

"If people with asthma are told they snore, they should talk to their physician about the possibility of sleep apnea," she added.